1. Field of the Invention
The present invention relates to an ink-jet printer, and more particularly, to a print head position adjusting apparatus of an ink-jet printer capable of adjusting an orientation of a print head mounted in a carrier, thereby preventing a stitching problem.
2. Description of the Related Art
There are many types of printers printing data or a file created by a user using a computer. For example, an ink-jet printer performs a printing process in a manner that a bubble, which is generated by heating ink stored in an ink cartridge constituting a print head (Hereinafter, it is referred to as “print head”), causes the ink to be ejected onto a sheet of paper through a nozzle in a predetermined pattern.
As shown in FIGS. 1 and 2, a conventional ink-jet printer 10 includes a paper feeding device 20 on which sheets of paper P are stacked, a conveying device 30 conveying the paper P from the paper feeding device 20, a printing device 40 having a print head 41 mounted in a carrier moving along a carrier shaft 42 in left and right directions to perform printing with respect to the paper P conveyed by the conveying device 30, and a discharging device 60 discharging the printed paper P from the printing device 40 to an outside of the ink-jet printer 10.
As shown in FIGS. 3 and 4, the ink jet printer 10 is provided with a balancing shaft 44 disposed at a lower portion of the carrier 46 to allow the print head 41 seated on a lower supporting portion 45 of the carrier 46 to be secured in position, in this instance, a position where a lower securing surface 23 of the print head 41 is in a parallel relationship with a carrier shaft 42, so that the ink can be precisely ejected onto the paper P while the print head 41 moves along the carrier shaft 42 to perform the printing.
Operations of the ink jet printer 10 having the above structure are described hereinbelow in conjunction with FIGS. 1 through 4. The paper P is stacked on the paper feeding device 20 and resiliently supported by a rock-up spring 21, is picked-up by a pickup roller 22, and then is supplied to the conveying device 30.
Next, the paper P is transferred to the printing device 40 by rotations of a feed roller 31 and a friction roller 32 of the conveying device 30. As the paper P is transferred from the conveying device 30 to the printing device 40, a carrier driving motor 47 is driven to activate a belt 43. Accordingly, while the carrier 46 moves along the carrier shaft 42 together with the print head 41, which is contained in the carrier 46 and has a nozzle 41a attached thereto to eject the ink, the print head 41 ejects the ink onto the paper P conveyed from the conveying device 30 to print data on the paper P.
The paper onto which the data is printed by the ink ejected from the nozzle 41a of the print head 41, moves on a base frame 50, gradually reaches the discharging device 60, and then is discharged through a discharging roller 61 and a star-shaped wheel 62.
However, in the conventional ink jet printer 10, the balancing shaft 44 allowing the print head 41 to be in position is secured to the carrier 46 and thus is not movable with respect to the carrier 46. Accordingly, when the securing surface 23 of the print head 41 is positioned with an improper orientation due to errors of fabrication and assembly of the ink jet printer 10, for example, when the securing surface 23 is not parallel to the balancing shaft 44 attached to the carrier 46 or when there occurs a misalignment, such as an unparallel relationship, between the balancing shaft 44 and the carrier shaft 42, there is no way to adjust the improper orientation of the printing head 41.
Also, even though the print head 41 is precisely positioned initially, the print head 41 becomes deviated from an initial position by a mechanical abrasion and a work load during a long time printing work and thus cannot maintain the parallel relationship with the balancing shaft 44 or the carrier shaft 42.
As described above, if the print head 41 cannot maintain the parallel relationship with the balancing shaft 44 or the carrier shaft 42, there occurs a stitching problem so that the ink ejected from the nozzle 41a of the print head 41 onto the paper P is skewed at each swath-to-swath boundary in a printed image, and thus a printing quality deteriorates. The stitching problem more seriously affects the image quality deterioration when the data to be printed relates to a perpendicular line or image.